Walkthrough part 17

Shotaro hangs out at a bar called the Shellac, which is in the Champion District. Follow your arrow and head over there. Inside the Shellac, there's no one but the bartender. Kazuma isn't psycho, so he questions the bartender with words instead of fists. Kazuma lies that he and Shotaro are friends, and then the bartender turns this into Who Wants To Be a Millionaire by asking what the most expensive drink on the menu is. The final answer is D: Bowmore 40 Years.

With that pointlessness over, the bartender finally admits that Shotaro worked for the Shellac, but quit. He left to work instead at a host bar called... Stardust. Oh joy.

Run all the way back across town back and enter the Stardust. Inside, Yuya owes Kazuma one, and helps him find Shotaro, going by Shota, is hanging out with Saya. Date shows up and confronts Saya while Shota cries in the corner. Saya eventually storms away, something she seems to be good at. Outside though, she's caught by a bunch of thugs. I think by now you'll know where this is going.

Date helps out here, and you'll make short work of the jerks. Date afterwards demands to see who sent them. We're not told where he went at first, as Date went by himself to see their "boss." Inside the Stardust, everyone else involved is worried, and Kazuma decides to find him.

As Kazuma heads out of the Stardust, all the truth comes out. Shota has a debt to pay off, and to appease the loan collectors, he told Saya to start selling herself to all available men. Looks like Shota's the jerk after all. Kazuma sets Saya straight, and demands to know where the loan shark is so he can settle up for all of them. The loan shark's name is Haruta, and has an office building nearby.